I. Field of the Invention
The present invention relates to a light panel and booth for facilitating automobile body repairs, and, more specifically, to such a light panel and booth in which patterned light is projected onto an automobile body through specially designed and colored lenses to highlight automobile body flaws and imperfections.
II. Description of the Related Art
It is often difficult to detect small dents and other imperfections in the surface of an automobile body by unaided eyesight. This is particularly true of new or newly painted automobiles viewed under artificial light, such as in automobile assembly plants or repair and paint shops. In such assembly plants and repair shops, it is important that even the smallest dent or imperfection be detected to provide for satisfied customers and dealers and to avoid adversely affecting the reputation of the plant or shop.
Several previous efforts have been made to produce inspection systems for metal surfaces which are designed to detect surface dents and scratches. Hugh Lippincott and Henry Stark, in an article entitled "Optical-digital detection of dents and scratches on specular metal surfaces" in Applied Optics, Aug. 15, 1982, describe a system in which a regular grid pattern is reflected off of a metal surface to be inspected, with the reflected image photographed by a video camera. The photographs are then digitally analyzed and compared against samples from a calibration sample from an unflawed surface with any large deviations indicating the presence of one or more dents. For scratch detection, the authors describe a gray level threshold analysis to detect background to scratch brightness contrasts. The system described in the Applied Optics article was designed for and appears to be most suitable for implementation in an environment in which relatively small manufactured appliances must be inspected automatically, with badly scratched or dented samples simply discarded or recycled.
A series of U.S. Patents describe a retroreflective surface inspection system and method, including U.S. Pat. No. 4,629,319 to Clarke et al., U.S. Pat. No. 5,168,322 to Clarke et al., and U.S. Pat. No. 5,206,700 to Reynolds et al., all of which are assigned to Diffracto, Ltd. of Windsor, Canada. In these patents, light from a slit or point source is swept across a surface to be inspected via a scanning mirror or the like. The light reflects off of the inspected surface, off of a retroreflective surface and back off of the inspected surface and then to a camera lens or the eye of an observer. The retroreflected image received by the camera or eye magnifies any dents or imperfections in the surface being inspected. These systems employ sophisticated robotic inspectors and require complex synchronization of the swept beam and the analyzing equipment. For use in an automobile assembly plant or the like, the patents illustrate an inspection system with multiple independent light emitters, reflectors and analyzers. In addition, these patents describe an inspection process in which inspected panels must first be covered with a thin coating of oil to enhance their reflective properties. This is an expensive and time consuming process. Finally, in the Diffracto systems, as well as the Lippincott and Stark article, a sophisticated digital analysis must be performed and interpreted, which effectively limits the possibility of immediate correction of detected dents or other defects.
It is clear then, that an effective apparatus and method is needed for highlighting flaws and imperfections in automobile bodies. Such an apparatus and method should be inexpensive and reliable, should allow flaws and imperfections to be detected quickly and efficiently by an ordinary observer, should be effective at highlighting flaws in automobiles of a wide variety of colors and should allow detected dents and blemishes to be repaired immediately during the inspection process.